An array camera is an array of individual cameras. Typically, the individual cameras cooperate to provide imaging functionality that cannot be achieved using one of the individual cameras alone. Array cameras have found use primarily in stereo imaging and surround or wide field-of-view (FOV) imaging. In stereo imaging, two individual cameras image the same scene from two slightly different vantage points to gain depth perception. In surround/wide-FOV imaging, two or more cameras placed at a common location are configured to view different portions of the surroundings, such that the cameras combine to provide an extended field of view as compared to that of a single camera. For example, several cameras on an automobile may face in different directions and cooperate to provide a 360 degree view of the surroundings.
More recently, array cameras have found new applications. One such application is dynamic zoom. In this application, the array camera includes one camera with a narrower field of view and another camera with a wider field of view. These two cameras are directed to view essentially the same scene, however with the narrower field-of-view camera providing a zoomed-in view of the scene. A pair of images captured by these two cameras may be combined to provide a range of zoom-levels, and this array camera thus has dynamic zoom capability, which otherwise, when using only a single camera, would require active mechanical adjustment of a variable imaging objective. In another application, an array camera includes a color camera and a monochrome camera having higher spatial resolution than the color camera. A color image of higher spatial resolution than that provided by the color camera itself may be obtained by utilizing the higher spatial resolution content provided by the monochrome camera. Array cameras may also be used in high dynamic range (HDR) imaging. Here, two individual cameras of the array camera, configured to view the same scene, capture images at different exposure times to improve the dynamic range over that of an individual camera. As compared to conventional HDR imaging based on a sequential image capture by a single camera, the array camera approach has the advantage that the two images are captured at the same time, which reduces the risk of motion artifacts commonly experienced in single camera based HDR imaging.
All of the above-mentioned new applications rely on proper combination (superposition) of images captured by two different cameras placed at slightly different positions and thus having slightly different views of the scene. Prior to image combination, purely geometrical corrections are applied to the captured images to rectify each of the captured images and align them with each other. The alignment process is based upon comparing pixel values between the individual images to find corresponding pixels. Frequently, imperfections in this image combination approach result in so-called ghosts in the combined images, that is, objects that appear misplaced or appear in duplicate in the combined image.